Seal for a discharge lamp

Abstract

The invention relates to an electric discharge lamp comprising:—a light-transmissive ceramic discharge vessel ( 1 ) enclosing a discharge space ( 100 )—a first and a second current conductor ( 2,3 ) entering the discharge vessel ( 1 ) and each supporting an electrode ( 4,5 ) in the discharge vessel ( 1 );—a sealing compound ( 6 ) sealing the current conductors ( 2,3 ) in the discharge vessel ( 1 ) in a gas tight manner,—an ionizable filling comprising a rare gas and metal halide in the discharge vessel ( 1 ), both current conductors ( 2,3 ) extending from the sealing compound ( 6 ) to the exterior of the discharge vessel ( 1 ). According to the invention the sealing

1 . An electric discharge lamp comprising: 
 a light-transmissive ceramic lamp discharge vessel enclosing a discharge space;    a first and a second current conductor entering the lamp discharge vessel and each supporting an electrode in the lamp discharge vessel;    a sealing compound forming a sealing of the lamp vessel around the current conductors in the discharge vessel in a gas tight manner; with both current conductors, extending from the sealing to the exterior of the discharge vessel,    an ionizable filling comprising a rare gas and metal halide in the lamp discharge vessel, both current conductors, extending from the sealing compound to the exterior of the lamp vessel, characterized in that the sealing compound is a sealing braze at least substantially and comprises a noble metal chosen from the group, preferably platinum, palladium, rhodium and iridiumor an alloy of a noble metal, preferably platinum, and niobium.    
     
     
         2 . An electric discharge lamp according to  claim 1  wherein the sealing braze also comprises an element chosen from the group formed by Ni, B, Si, Ti, Zr, Y and Nb.  
     
     
         3 . An electric discharge lamp according to  claim 1  wherein wherein the sealing braze metals Pt, Pd, Rh and Ir are comprised in an atom percentage ≧45.  
     
     
         4 . An electric discharge lamp according to  claim 1  wherein the discharge vessel is free of extended plugs.  
     
     
         5 . An electric discharge lamp according to  claim 1  wherein one of the first and second current conductor is provided at the location where it extends from the sealing to the exterior of the discharge vessel with a coil extending away from the discharge vessel.  
     
     
         6 . An electric discharge lamp according to  claim 1  wherein the discharge vessel at the location of the sealing braze is provided with a metal coating of a refractory metal, preferably chosen from W and Mo.  
     
     
         7 . An electric discharge lamp according to  claim 1  wherein the discharge vessel at the location of the sealing braze is formed as a cermet.